Each sentinel lymph node will be serially sectioned at 2mm intervals parallel to the long axis and totally submitted for histologic evaluation in one or more blocks. From each block, five slides will be cut at 100 micron intervals and stained with hematoxylin and eosin. A parallel slide at each level will be cut and held for batch cytokeratin AE1/AE3 immunohistochemical staining if negative for metastasis by initial H&E staining. The largest dimension of each metastasis will be measured and recorded in order to track the presence of micrometastasis defined as a metastatic focus less than 2mm in size.